The cardiovascular status of a patient that is being mechanically ventilated is important to medical care practitioners in order to provide adequate monitoring and treatment of the patient. Several techniques have been used to assess cardiac function, such as measurement of central venous pressure by a catheter that is introduced through a vein into the right atrium and measurement of the pulmonary capillary wedge pressure by the insertion of a Swan-Ganz catheter (a balloon-tipped pulmonary artery catheter).
Calculations made from systolic blood pressure waveforms are also used to assess cardiac function in mechanically ventilated patients. However, acquiring these calculations requires manipulation of the ventilator, i.e., turning the ventilator off for a period of time to generate an apneic episode. This method prevents the continuous measurement of the systolic blood pressure.